Patents are indicators of the organization’s output and reflect its level of technological development. Today they have become a key commercial asset, which is why there is increasing interest in their study from the perspective of their monetary value and their economic use. However, the exact number of actually used patents and their actual implementation is not known. In this study, the level of commercialization of Spanish patents granted by the Spanish Patent and Trademark Office (SPTO) during the period 1996-2006, and their rate of economic return has been identified and analysed for the agents developing them. The results obtained show there is still a wide margin for the economic agents to make more efficient use of this intellectual property tool.